Sterlingb06
Member
I have found that an accurate load can be defined by muzzle velocity and seating depth (for a given bullet). The right muzzle velocity will be determined by a node of constant speed while making slight changes in powder weight. Find the right seating depth by staying in the middle of the velocity/powder weight node and picking the most accurate one.
You don't need to wait for fully fire formed brass or for the barrel to settle out, do your load development from the start. As long as you are capturing this data (MV and seating depth), you should be 90% to the final answer when things settle out and brass formed.
Now, how much powder you need to maintain that velocity will probably change in new brass vs fire formed, as the barrel settles out, if you change lot number of powder (or even powder type as long as it has somewhat similar burn rates). Muzzle velocity is all about barrel harmonics - you are trying to get the bullet out of the muzzle when the barrel has the most upward flex (as the muzzle flexes up and down many times when you fire, there are different velocity nodes at which the bullet leaves the barrel at the right time).
You can even change to a different brand of brass and get back into the sweet spot for a load if you can match the speed and seating depth from the first load development. Now when doing this, you have to be super careful. Some brass shows signs of pressure earlier than others (and you might not get to you node) or the charge weight for the same speed is as much as 1 gr off. WHEN CHANGING COMPONENTS IN A LOAD - BACK OFF CHARGE AND WORK UP.
Final statement - some people chase seating depth as the throat wears. I have not seen a dramatic change in accuracy as throat wears so I leave my seating depth alone. I also don't hot rod my loads or fire fast to have fast erosion.
You don't need to wait for fully fire formed brass or for the barrel to settle out, do your load development from the start. As long as you are capturing this data (MV and seating depth), you should be 90% to the final answer when things settle out and brass formed.
Now, how much powder you need to maintain that velocity will probably change in new brass vs fire formed, as the barrel settles out, if you change lot number of powder (or even powder type as long as it has somewhat similar burn rates). Muzzle velocity is all about barrel harmonics - you are trying to get the bullet out of the muzzle when the barrel has the most upward flex (as the muzzle flexes up and down many times when you fire, there are different velocity nodes at which the bullet leaves the barrel at the right time).
You can even change to a different brand of brass and get back into the sweet spot for a load if you can match the speed and seating depth from the first load development. Now when doing this, you have to be super careful. Some brass shows signs of pressure earlier than others (and you might not get to you node) or the charge weight for the same speed is as much as 1 gr off. WHEN CHANGING COMPONENTS IN A LOAD - BACK OFF CHARGE AND WORK UP.
Final statement - some people chase seating depth as the throat wears. I have not seen a dramatic change in accuracy as throat wears so I leave my seating depth alone. I also don't hot rod my loads or fire fast to have fast erosion.
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